Mermaid weed

Proserpinaca palustris

Also known as Marsh mermaidweed, Proserpinaca palustris 'Cuba'

FreshwaterStemCuttingsSide shoots

Care at a glance

Light: High light
CO2: CO₂ required
Temperature: 64–81°F; 18–27°C
Max height: 11.8 in; 30 cm

Growth rate: Medium
Placement: Midground
Type: Stem
pH: 5.0–7.5
Hardness: 0–12 dGH
Spread: 3.1 in (8 cm)
Nutrient uptake: Root + water column
Growth region: Submersed or emersed
Difficulty: Medium
Family: Haloragaceae
Origin: Eastern and southern USA, Caribbean, Central and northern South America

Overview

Mermaid weed is a midground stem plant of medium difficulty, prized for its feathery submersed leaves.

Did you know

Mermaid weed changes its leaves so much underwater that growers sometimes think they were sold the wrong plant. Above water it makes plain saw-toothed leaves. Underwater it grows delicate fern-like combs that flush orange under bright light.

Caring for mermaid weed

Strip the lower leaves and plant the stems one at a time, with room around each, in a nutrient-rich substrate. Freshly imported plants are grown emersed and take weeks to convert to the submersed form, so be patient.

Mermaid weed needs high light and injected CO2 to develop its orange-to-red feathery submersed leaves. In low light and without CO2 it stays green and grows poorly. Feed both the roots and the water, with root tabs and a liquid fertilizer. It handles 64 to 81°F (18 to 27°C).

It grows at a moderate pace and makes few side shoots. Propagate it by topping the stems and replanting the cuttings.

Good to know

Mermaid weed is a member of the watermilfoil family, Haloragaceae. Botanists call it strongly heterophyllous, and its finely divided, comb-like submersed leaves are termed pectinate. The 'Cuba' form that made it popular was imported by Tropica.

In the wild

Mermaid weed grows in swamps, ditches, pond margins and seasonally flooded ground throughout the eastern and southern United States. It also reaches the Caribbean islands and parts of Central and South America. In the wild it grows as an emersed marsh plant.

Common questions

Does mermaid weed need to be planted in the substrate?

Yes. Strip the leaves from the lower part of each stem, then push the stems into the substrate one at a time, a little apart.

Does mermaid weed need CO2?

Yes. Mermaid weed needs injected CO2 to grow well, and it usually struggles without it.

How much light does mermaid weed need?

Mermaid weed needs high light from a strong planted-tank LED. In weaker light its stems stretch and drop their lower leaves.

Does mermaid weed need root tabs?

They help. Mermaid weed takes nutrients through both its roots and its leaves. Root tabs near its roots and a liquid fertilizer cover both.

How do you propagate mermaid weed?

Mermaid weed propagates by cuttings and side shoots. Cut off the top of a stem and replant it, and the stump left behind grows new shoots. Cut a side shoot off once it has a few leaves and plant it on its own.